World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural

Regional groundwater flow modeling in Western Nile Delta,

Rani Fouad Mohamed (1), (2), Chen Zhi Hua (1)

(1) School of Environmental Studies, China University of Geosciences, 388 Lumo Road, Wuchang,Wuhan, Hubei, P.R.China; Zip code: 430074. (2) Faculty of Engineering, Alazhar University, Nasr city, , Egypt; Zip code: 11341 [email protected]; Tel: 00862762626996

Abstract: Western Nile delta is an important area in Egypt in which the government plans to establish new reclamation projects. The already present agricultural activities are mainly based on groundwater for irrigation. However, irrigation requirements have become so large that they cause depletion of the groundwater levels in most of the existed wells. A hydrogeological model for western Nile delta has been developed using MODFLOW code. The developed model was calibrated for steady state, and used to evaluate groundwater potentiality and reserves. The results have shown that; a reduction in groundwater abstraction by at least 20% becomes necessary to achieve sustainable conditions. This study can be considered as a preliminary regional evaluation for testing the future alternative water management scenarios in Western Nile Delta area. [Rani Fouad Mohamed, Chen Zhi Hua. Regional groundwater flow modeling in Western Nile Delta, Egypt. World Rural Observations 2010;2(2):37-42]; ISSN: 1944-6543 (Print); ISSN: 1944-6551 (Online). http://www.sciencepub.net/rural.

Keywords: Groundwater modeling, Groundwater/surface-water interaction, western Nile delta.

Introduction the Qattara Depression, the study area covers about Groundwater is an important source for water 15170.6 km2 as shown in Figure [1]. supply in Egypt, Nile water alone is no longer sufficient for the increasing water requirements for Hydrogeological setting different development activities. However, many Western Nile Delta region distinguished into cautions and worries are increasingly being voiced on three aquifers, Quaternary aquifer, Pliocene aquifer and the dangers that surround the groundwater resources. the Moghra aquifer. The main aquifer in the Nile Delta The main elements of these worries are related to is the Quaternary aquifer. The saturated thickness of depletion as a result of over abstraction. Western Nile Quaternary aquifer ranges between 50 m along the delta has limited water resources although it lies on the desert fringes in the West to 800 m in the North while western part of Nile Delta aquifer. The government it reaches about 200 m in the South near El Kanter El established canals network to divert surface water to Khiria City. The aquifer is semi-confined in the Delta area, this area but farmer still suffering from shortage of being overlain by a Holocene layer of sandy clay and silt, surface water and use the groundwater wells. There are and in the area of Nubaria, where aquifer is covered by more wells operating within the basin. Due to excess loamy deposits. In the rest of the area, the aquifer is abstraction from these public and private wells (1.90 phreatic (unconfined). The Moghra aquifer is the main BCM), the water level in the well fields declined aquifer in the southern and western portions of the study significantly. Water table’s decrease leads to salt-water area. The aquifer is overlain by Pliocene and underlain by intrusion with the Mediterranean Sea. The farms Oligocene basalt or shales. Both aquifers are connected become covered with the saline water RIGW/IWACO with each other in a direct hydraulic contact along the (1998). To avoid the deterioration of the aquifer system stretch Khatatba-Abu Rawash (lateral) and along the in this area an efficient integrated and sustainable stretch -Khatatba (vertical). While in all other management plan for groundwater resources is needed. locations, the two-aquifer systems are separated by Groundwater modeling is the best tool to predict the Pliocene deposits. response of the groundwater aquifer and estimate the The piezometric head level of groundwater is safe yield (Xuesen Mao et al., 2005). generally decreasing within the Western Nile Delta from more than 15 m +MSL in Cairo to 1 m +MSL Study area near the coast. The piezometric level decreases from Western Nile Delta region occupies the area south to north by an average piezometric gradient about between Cairo at equator and , west of 0.00011. The groundwater levels are usually oscillating branch, and extends westward to the desert area up and down affected by one or more of the following, from the west of Wadi el-Natrun up to the eastern edge of levels of water in the river Nile and its distributors, method and frequency of irrigation, horizontal and

37 World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural vertical agricultural extensions, and groundwater extraction by wells are the main discharge components extraction. from the aquifer. In 1985 the annual abstraction for Recharge to the aquifer takes place due to three both drinking water and irrigation was 460 million factors Infiltration, Infiltration and downward leakage cubic meters and increased to 635 million cubic meters of excess surface irrigation water (originating from the in 1997. Due to increase in desert fringes reclamation River Nile) and, Leakage from canals. in the Western Nile Delta region in the end of nineties, Discharge of groundwater takes place through the abstraction from groundwater increased four processes: outflow into the drainage system, direct dramatically to 1370 million cubic meters. The recent abstraction, evapotranspiration and inter-aquifer flow filed investigations estimate current abstraction as 1.9 of groundwater. Groundwater return flow to the river BCM. Nile and drains (open drains and tile drains) as well as

29 30 30 00 30 30 Lake Burulus 31 00

Rashid Mediterranean Sea (Rosetta) Abo QIR Edko El Monatazah Alexandria ( Kafr R El Mahmudya o Selim s N Kaffr El Dauwar et i El Dekhila ta le North Abu Hummus b r an c Shubra Khit h) Behira 31 00 Hosh Isa Burg El Arab Abo El Matamir Itay El Barod El Delingat

Kom Hamada Mudiriyat Eltahrir

Talet Elgarw Mudiriyet el Tahrir Gabel Naum Liberation Provience

W a di El N a El Khatatba 30 30 tr un Sadat City Banha Gabel Hadid Khasm Elkalb

Gabel Qentara Wadi El Farigh Legend Gabel Rozza Gabel Gubr Cairo Main Roads City Railway Sutdy Area Scale 1 : 1.000.000 30 0029 30 30 0029 30 30 31 00

Figure [1], Western Nile Delta Location

Model development Model set-up To develop the numerical simulation for the aquifer system MODFLOW code has been selected to simulate three dimensional steady state groundwater flows for the study area. The model consists of multi-layers aquifer system. The first layer represents the semi-confining layer (upper clay layer), which overlies the main aquifer. It is modeled as an aquifer in which vertical and horizontal flows simulated. A finite difference grid is generated for the modeled area. The grid consists of 100 rows and 100 columns, for a total of 10 000 cells. All of the cells have uniform dimensions of 1.6 km by 1.6 km; the cell size is small enough to reflect both the density of input data and the desired output detail, and large enough for the model to be manageable. All surface water features such as the river, main irrigation canals and main open drains are simulated as ‘rivers’ in the model. The exchange between those ‘rivers’ and the aquifer systems is calculated with Darcy’s equation, and expressed as follows:

K q v D= H [1] b

Equation (1) can be rewritten in the following form:

38 World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural

)H - H ( C Q = C ( H - aquiferriverrch )H [2] K and C = v [3] b

where q is the flow between the river and the aquifer (positive for baseflow - for gaining streams and negative for river recharge – for losing streams); C is a constant representing the streambed leakage coefficient K (hydraulic conductivity of semi-impervious streambed stratum v divided by its thickness b); and DH is the difference between the water level in the river H river and the groundwater level in aquifer H aquifer .

Boundary conditions The aquifer boundaries can be described by two types of hydrological conditions. No flow boundary is applied for the southern boundary where a fault exists and previous studies showed that no flow can be from the western desert enters the aquifer system (Mohamed A. et al., 2005). Constant head boundary is used for the eastern, northern and western boundaries; the constant head data were obtained from hydrogeologic map for the Nile delta, as shown in Figure [2].

971502 Mediterranean Sea

Alexandria (R o s N e i tt le West Nile Delta a br an Damanhur ch North 930000 )

Tanta

900000

870000

North Western Desert

840000 Legend Cairo

Contour line Scale 1 : 1.000.000 809492 470586 540000 570000 600000 638475510000

Figure [2], Constant head in Western Nile Delta

Model calibration model development. The only parameters contributing The numerical model was calibrated under to the uncertainty of the model simulations were: (a) steady-state conditions through a series of groundwater the hydraulic conductivity, and (b) the distribution of flow simulations. The conceptualization of the regional the areal recharge rate. . Fig. [1] Shows the initial flow and the relatively complex model architecture hydraulic conductivity distribution for the aquifer were precisely defined in the preliminary stage of the system. During the calibration, the simulated recharge

39 World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural distribution was depend on the following values, In the average; the simulated water level differs by about 30 central and southern portions of the flood plain, the cm from the observed water level. Errors are generally downward leakage towards the aquifer ranges between spread across the model area with only a limited 0.25 and 0.8 mm/day, depending on the soil type, number of areas where values are consistently higher or irrigation and drainage practices. In the desert areas, lower than simulated water levels. relatively high leakage rates are observed for basin, The final values for hydraulic conductivity furrow and sprinkler irrigation (1.0–1.5 mm/day) with were not changed because they provided a good match much lower rates for drip and central pivot irrigation between simulated and observed heads together with (0.1–0.5 mm/day) RIGW/IWACO (1998). The the solid ground from which they were induced. calibration was performed by trial and error until Streambed conductance was increased by a factor of achieving a reasonable agreement between the about three to increase the interaction between streams simulated heads and the measured groundwater levels and the aquifers. Large increases or decreases in the observed in (1992) value had the effect of draining the groundwater system or isolating it, respectively. Adjustment of river Model Stability and Sensitivity Analysis conductance and canals conductance had minimal Sensitivity analysis is conducted on a number effect on the model runs. Canals conductance of parameters including recharge, hydraulic adjustment had minimal impact due to the limited conductivity, and vertical leakance for the Nile Delta number of significant canals. Drains were included aquifer. Two runs done two check the model sensitivity primarily to insure that the model could discharge to hydraulic conductivity using factors (0.1, 10) from water over a large area if the water level exceeded the the original calibrated values of hydraulic conductivity. land surface elevation. Using one tenth of the permeability increase the dry In spite of extensive water pumping and cells at the western part of the model and limiting the reasonable recharge amounts in northwestern part in aquifer active zone to be much near to the Rosetta the study area, it contains the highest water levels. The branch. While the values of ten times the permeability analysis indicated that this might be due to small widely spread the piezometric head over the modeled thickness of the aquifer and the elevated aquifer base in area. Sensitivity of the model due to recharge also this area. According to the calibrated model, the rate of checked by using factors (0.5, 2) from calibrated recharge entering the aquifer approximately is 1.54 recharge values. using one half of recharge also BCM. The water budget indicated that, the influx and increase the dry cells at the western part of the model out fluxes along the model boundaries, are 0.16 BCM and limiting the active zone to be much near to the and 0.3 BCM respectively. The velocity vectors Rosetta branch as occurred when permeability was distribution indicated the variations in magnitude and taken one tenth. While two times of recharge values directions inside the modeled area as shown in Figure increase the groundwater levels over the whole [3]. Velocity vectors distribution showed the in and out modeled area. Sensitivity analysis performed by fluxes directions along the model boundaries. changing one parameter values at a time and noting the effects of the parameter change on the simulated Model limitations groundwater levels. The numerical model developed in this study represents an interpretation and a simplification of Results and discussion observed field conditions. Seasonal variations or other Results of 16 water level observations wells changes in the flow conditions were not accounted for. were used to evaluate the performance of the A model calibration under transient flow conditions predevelopment model. The simulated water levels and based on the observed groundwater fluctuations generated by the calibrated model matched the can be the next stage in improving the regional flow observed water levels quite well. The RMS is 7.5%, on model.

40 World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural

971502 Mediterranean Sea

Alexandria (R o s N e i tt le West Nile Delta a br an Damanhur ch North

930000 )

Tanta

900000

870000

North Western Desert

840000 Legend Cairo Constant head contour line. Velocity vector. Scale 1 : 1.000.000 809492 470586 540000 570000 600000 638475510000

Fig. [3], Velocity vectors distribution

Summery and Conclusions This model and obtained results can be A steady state model has been developed to considered as preliminary regional evaluation for simulate the water resources in the Western Nile Delta. testing the alternative water management scenarios in Low vertical permeability of the top clay layer affects Western Nile Delta area the rate of infiltration from the main canals and to the main drains. So, the infiltration from these canals is References: small compared with gain of the aquifer system from 1-Charles V. Camp1, James E. Outlaw Jr.1 Michael C. Rosetta branch. Due to the direct hydraulic contact Brown, 2008. GIS-Based Groundwater Modeling. between the surface water bodies and the Nile delta Computer-Aided Civil and Infrastructure aquifer, any change in the flow and water levels will Engineering, 9 (4) Pp. 281 – 293 affect the groundwater levels and the regional water doi:10.1111/j.1467-8667.1994.tb00336.x balance due to the surface water/groundwater 2-Chen-Wuing Liu, Chun-Nan Lin, Cheng-Shin Jang, interaction and the complex flow system. The analysis Chan-Po Chen, Jen-Fu Chang, Chen-Chun Fan, indicated the highest water levels in northwestern part Kuo-Hiang Lou, 2006. Sustainable groundwater in the study area are due to small thickness of the management in Kinmen Island. Hydrological aquifer. The rate of recharge entering the aquifer is Processes, 20 (20) Pp. 4363 – 4372 approximately 1.54 BCM. The water budget indicated doi:10.1002/hyp.6171 that, the values of in and out constant head along the 3-D. Peyrard 1 *, S. Sauvage 1, P. Vervier 1, J. M. model boundaries are 0.16 BCM and 0.3 BCM Sanchez-Perez 1, M. Quintard, 2008. A coupled respectively. The results show that the situation is far vertically integrated model to describe lateral from sustainable, because the total amount of exchanges between surface and subsurface in large groundwater abstraction for irrigation (1.9 BCM) is alluvial floodplains with a fully penetrating river. . larger than the groundwater recharge, which in the long Hydrological Processes, 22 (21) Pp. 4257 – 4273 term will undermine the capacity and sustainability of doi:10.1002/hyp.7035 the aquifer, and will lead to salt water intrusion. It is 4-Hilmar Hofmann , Kay Knöller , Dieter Lessmann, proposed that groundwater abstraction should be 2008. Mining lakes as groundwater-dominated diminished with 20% in order to reach a sustainable hydrological systems: assessment of the water situation. balance of Mining Lake Plessa 117 (Lusatia,

41 World Rural Observations 2010, 2(2) http://www.sciencepub.net/rural

Germany) using stable isotopes. Hydrological evapotranspiration. Journal of groundwater, 22 (16) Processes, 22 (23) Pp. 4620 – 4627 Pp. 2993 – 3009 doi:10.1002/hyp.7071 12-OSMAN Yassin Z. and BRUEN Michael P., 2002. 5-J. Butler Jr., Vitaly A. Zlotnik, and Ming-Shu Tsou., Modelling stream-aquifer seepage in an alluvial 2001. Drawdown and Stream Depletion Produced aquifer: An improved loosing-stream package by Pumping in the Vicinity of a Partially for MODFLOW. Journal of hydrology, 264, Pp. Penetrating Stream. Journal of ground water, 39 69-86 DOI:10.1016/S0022-1694(02)00067-7 (5), Pp. 651-659 DOI:10.1111/j.1745- 13-RIGW, 1992, ‘Hydrogeological map for the Nile 6584.2001.tb02354.x Delta area’, Scale 1: 500000. Research Institute for 6-J. W. N. Smith, M. Bonell, J. Gibert , W. H. groundwater, El Kanter El Khairia, Egypt. McDowell, E. A. Sudicky, J. V. Turner, R. C. 14-RIGW/IWACO, 1998, ‘Environmental management Harris, 2007. Groundwater-surface water of groundwater resources (EMGR): Identification, interactions, nutrient fluxes and ecological priority setting and selection of area for monitoring response in river corridors: Translating science groundwater quality’, Technical Report into effective environmental management. TN/70.00067/WQM/97/20, Research Institute for Hydrological Processes, 22 (1) Pp. 151-157 Groundwater (RIGW), Egypt. DOI:10.1002/hyp.6902 15-Sophocleous M., 2000. From safe yield to 7-LaBolle EM, Ahmed AA, Fogg GE. 2003. Review of sustainable development of water resources the the Integrated Groundwater and Surface-Water Kansas experience. Journal of hydrology, 235, Pp. Model (IGSM). Journal of ground water, 41 (2), 27-43 DOI:10.1016/S0022-1694(00)00263-8 Pp238-246 DOI:10.1111/j.1745- 16-Stefan Krause, Axel Bronstert, 2006. The impact of 6584.2003.tb02587.x groundwater-surface water interactions on the 8-Leonard F. K., Thomas E. R., (1999): “The water balance of a mesoscale lowland river Handbook Of Groundwater Engineering” Chapter catchment in northeastern Germany. Hydrological [20], “ Groundwater Modeling” ISBN 3-540- Processes, 21 (2) Pp. 169-184 64745-7. Www.Springer.De DOI:10.1002/hyp.6182 9-Min Sun Chunmiao Zheng , 2007. Long-Term 17-Xiangjiang Huang, Jeffrey D. Niemann, 2006. Groundwater Management By A Modflow Based Modelling the potential impacts of groundwater Dynamic Optimization Tooljawra Journal of the hydrology on long-term drainage basin evolution. American Water Resources Association, 35 (1) Pp. Earth Surface Processes and Landforms, 31 (14) 99 – 111 DOI:10.1111/j.1752- Pp. 1802 – 1823 DOI:10.1002/esp.1369 1688.1999.tb05455.x 18-Xuesen Mao, Jinsheng Jia , Changming Liu , 10-Mohamed A. Dawoud, Madiha M. Darwish, Mona Zhimin Hou. , 2005. A simulation and prediction M. El-Kady, 2005. GIS-Based Groundwater of agricultural irrigation on groundwater in well Management Model for Western Nile Delta. Water irrigation area of the piedmont of Mt. Taihang, Resources Management, 19, Pp. 585–604 DOI: North China. Hydrological Processes, 19 (10) Pp. 10.1007/s11269-005-5603-z 2071 – 2084 doi:10.1002/hyp.5667. 11-Osman A. E. Abdalla, 2007. Groundwater discharge mechanism in semi-arid regions and the role of

1/5/2010

42